Process and apparatus utilizing common structure for combustion, gas fixation, or waste heat recovery

Abstract

An enclosure containing rotating blades for mechanical stirring of gaseous fluids may be a heat exchanger, flue gas energy recovery device, gas generator or combustion device. A high rotational stirring velocity increases the convective heat transfer rate, rendering it independent of the lower throughput velocity of primary fluid which can be controlled independently of the stirring speed. Primary fluid is isolated from a secondary fluid by a thermal transfer surface which is continuously swept by the swirling primary fluid and which may be the peripheral wall of the enclosure or a flow tube located proximate the peripheral wall. In one embodiment, swirling is achieved by radially-extending blade assemblies secured to a rotatable shaft at longitudinally spaced locations to establish discrete swirling zones in which fluid recirculates from the shaft outwardly, along the wall, and back toward the shaft. In another embodiment, the blades extend longitudinally, proximate the peripheral wall, from peripheries of horizontal discs which rotate with the shaft. In this embodiment, primary fluid follows a restricted helical path, maintaining continuous contact with the thermal transfer surface, away from the shaft. Either embodiment may be converted to a combustion system by igniting primary fluid in the presence of admitted air. In all embodiments, recirculation of primary fluid condensate, injected water or additive optimizes heat transfer via latent heat of vaporization and dropwise condensation. Blade rotary speed may be varied to commonly or independently control: combustion fuel and air flow; primary fluid flow; and stirring energy.

I claim: 
     
       1. In a thermal system, apparatus for increasing convection efficiency, comprising: an enclosure having an inlet opening, an outlet opening, and a predetermined longitudinal axis;   means for supplying a substantially gaseous primary fluid at said inlet opening;   means for establishing a static pressure differential between said inlet and outlet openings to establish a continuous net flow of primary fluid longitudinally through said enclosure;   a thermal transfer wall exposed to said primary fluid in said enclosure;   means containing a secondary fluid in flow isolation from said primary fluid and in thermal conduction relationship with said primary fluid through said thermal transfer wall; and   rotatable means for mechanically stirring said primary fluid in said enclosure, said rotatable means including drive means and blade means driven by said drive means for imparting at least one rotative flow component to said primary fluid along said thermal transfer wall with a flow rate substantially greater than the primary fluid net flow rate from said inlet opening to said outlet opening caused by said pressure differential.   
     
     
       2. The apparatus according to claim 1 wherein said apparatus is a heat exchanger and further comprises: a closed flow path;   secondary flow means for flowing said secondary fluid through said closed flow path;   said closed flow path including at least said thermal transfer wall positioned in the path of said rotative flow component of said primary fluid, said thermal transfer wall being fabricated of a material which readily transfers thermal energy between said primary and secondary fluids and provides flow isolation between said fluids.   
     
     
       3. The apparatus according to claim 2 wherein said closed flow path comprises an annular region surrounding said enclosure and having a radially inner wall which serves as both said thermal transfer wall and as a peripheral wall for said enclosure. 
     
     
       4. The apparatus according to claim 2: wherein said pressure differential establishes a net flow of said primary fluid in a first longitudinal direction through said enclosure; and   wherein said secondary flow means comprises means for establishing a net flow of said secondary fluid in a second longitudinal direction through said enclosed flow path, said second longitudinal direction being opposite said first longitudinal direction.   
     
     
       5. The apparatus according to claim 1 wherein said rotatable means comprises: a rotatable shaft extending along said longitudinal axis;   a plurality of discs extending radially from said shaft at a respective plurality of spaced longitudinal positions along said shaft;   wherein said blade means are plural blade members extending longitudinally through said enclosure and secured to each of said discs proximate the disc peripheries; and   means responsive to said drive means for rotating said blade members and discs together with said shaft.   
     
     
       6. The apparatus according to claim 5 wherein: said enclosure is generally cylindrical;   said longitudinal axis is the central longitudinal axis of said generally cylindrical enclosure; and   each of said blade members has a radially outermost edge which is substantially parallel to said longitudinal axis.   
     
     
       7. The apparatus according to claim 6 wherein said means for establishing a pressure differential comprises exhauster blade means secured to said rotatable shaft in said enclosure for forcing fluid flow from said inlet opening to said outlet opening. 
     
     
       8. The apparatus according to claim 7 wherein said rotatable means comprises: a rotatable shaft coupled in driven relationship with said drive means and extending along said longitudinal axis;   wherein said blade means includes a plurality of blade assemblies secured to said shaft at a respective plurality of spaced positions along said shaft, each blade assembly comprising:   plural blade members extending radially from said shaft; and   means for fixedly positioning said blade members relative to said shaft to assure common rotation of said blade members with said shaft about said longitudinal axis.   
     
     
       9. The apparatus according to claim 8 wherein said blade members are substantially longer in the radial direction than in the longitudinal direction in said enclosure, and wherein each blade member includes a generally flat surface extending parallel to said longitudinal axis. 
     
     
       10. The apparatus according to claim 8 wherein said enclosure is generally cylindrical, wherein said longitudinal axis is a central longitudinal axis of said cylindrical enclosure, and wherein said rotatable shaft is disposed concentrically about said longitudinal axis. 
     
     
       11. The apparatus according to claim 10 wherein said means for establishing a pressure differential comprises exhauster blade means secured to and driven by said rotatable shaft in said enclosure for exhausting fluid flow from said inlet opening through said outlet opening. 
     
     
       12. The apparatus according to claim 8: wherein said pressure differential establishes a net flow of said primary fluid in a first longitudinal direction through said enclosure; and   wherein said secondary flow means comprises means for establishing flow of said secondary fluid in a second longitudinal direction through said enclosed flow path, said second longitudinal direction being opposite said first longitudinal direction.   
     
     
       13. The apparatus according to claim 1 wherein said rotatable means comprises: a rotatable shaft extending along said longitudinal axis:   means coupling said shaft to said drive means for rotating said shaft about said longitudinal axis; and   zone-establishing means responsive to rotation of said shaft for establishing a plurality of thermal zones at successive longitudinal locations in said enclosure, said zone-establishing means including: means for swirling the primary fluid in each zone along a path which includes said thermal wall; and   means for progressively graduating the temperatures in successive zones along the length of said enclosure from said inlet opening toward said outlet opening.     
     
     
       14. The apparatus according to claim 1 wherein said enclosure is oriented with said longitudinal axis extending vertically. 
     
     
       15. The apparatus according to claim 1 operated as an economizer, wherein said means for supplying a primary gaseous fluid in a combustion system and said primary fluid corresponds to hot combustion gases exhausted from said combustion system; said apparatus further comprising: means for delivering said primary fluid from said outlet opening to the ambient environment; and   means for controlling the net flow of primary flow through said enclosure to control the exhausting of combustion gases from said combustion system.   
     
     
       16. The apparatus according to claim 15 wherein said rotatable means comprises: a rotatable shaft extending along said longitudinal axis;   a plurality of discs and extending radially from said shaft at a respective plurality of spaced longitudinal positions along said shaft;   wherein said blade means are plural blade members extending longitudinally through said enclosure and secured to each of said discs proximate the disc peripheries; and   means coupling said shaft to said drive means for rotating said blade members and discs together with said shaft.   
     
     
       17. The apparatus according to claim 15 wherein said rotatable means comprises: a rotatable shaft coupled in driven relationship to said drive means and extending along said longitudinal axis;   wherein said blade means includes a plurality of blade assemblies secured to said shaft at a respective plurality of spaced positions along said shaft, each blade assembly comprising:   plural blade members extending radially from said shaft; and   means for fixedly positioning said blade members relative to said shaft to assure common rotation of said blade members with said shaft about said longitudinal axis.   
     
     
       18. The apparatus according to claim 1 operated as an economizer wherein: said means for supplying a primary gaseous fluid is a combustion system; and   said primary gaseous fluid corresponds to the combustion gases exhausted from said combustion system; and   wherein said apparatus further comprises means for flowing said secondary fluid through said combustion system, after it has passed through said closed flow path, to utilize thermal energy in said secondary fluid which has been transferred thereto from said primary fluid.   
     
     
       19. The apparatus according to claim 1 wherein said rotatable means is rotatable in one direction only. 
     
     
       20. The apparatus according to claim 1 wherein said primary fluid is a gas which includes water vapor as a part thereof, and wherein said rotatable means includes: means for condensing said water vapor on said thermal transfer wall;   means for sweeping condensed water back into the rotating primary fluid flow; and   means for vaporizing the water swept back into the rotating flow;   whereby to establish a repetitive cycle of condensation and vaporization along said thermal transfer wall.   
     
     
       21. The apparatus according to claim 1 wherein said primary fluid is made up of hot combustion gases and wherein said blade means includes: a drive shaft, rotatably driven by said drive means, extending longitudinally through said enclosure along said longitudinal axis; and   means for forcing said hot combustion gases away from said drive shaft to prevent overheating of the drive shaft.   
     
     
       22. The apparatus according to claim 21 wherein said means for forcing includes said blade means, said blade means including: a plurality of blades;   means supporting said blades in longitudinally-extending positions in said enclosure, radially spaced from said drive shaft and angularly spaced from one another;   means coupling said drive shaft to said drive means for rotating said drive shaft at relatively high speeds, compared to said continuous net flow, about said longitudinal axis; and   means securing said supporting means and blades to said drive shaft for rotation therewith about said longitudinal axis.   
     
     
       23. The apparatus according to claim 22 wherein said drive means rotates said drive shaft in one direction at speeds in excess of 1500 revolutions per minute. 
     
     
       24. The apparatus according to claim 22 wherein said blades, said supporting means and said securing means comprise a separable unitary and substantially rigid structure. 
     
     
       25. The apparatus according to claims 1 wherein said longitudinal axis is oriented vertically, and wherein said outlet opening is disposed below said inlet opening. 
     
     
       26. In a thermal system, apparatus for increasing convection efficiency, comprising: an enclosure having an inlet opening, an outlet opening, and a predetermined longitudinal axis;   means for supplying a substantially gaseous primary fluid at said inlet opening;   means for establishing a static pressure differential between said inlet and outlet openings to cause said primary fluid to flow continuously through said enclosure;   a thermal transfer wall exposed to said primary fluid in said enclosure;   means containing a secondary fluid in flow isolation from said primary fluid and in thermal conduction relationship with said primary fluid through said thermal transfer wall; and   means for establishing a highly turbulent and relatively low thermal transfer resistant film of said primary fluid on said thermal transfer wall in said enclosure, said last-mentioned means comprising rotatable blade means for swirling said primary fluid at high velocities along said thermal transfer wall.   
     
     
       27. The apparatus according to claim 26 wherein said rotatable blade means comprises a plurality of blades rotatable about said longitudinal axis and drive means for rotating said blades in one direction at speeds in excess of 1500 revolutions per minute. 
     
     
       28. In a thermal system, apparatus for increasing convection efficiency, comprising: an enclosure having an inlet opening, an outlet opening, and a predetermined longitudinal axis;   means for supplying a substantially gaseous hot primary fluid at said inlet opening, said gaseous primary fluid having water vapor therein;   means for establishing a pressure differential between said inlet and outlet openings to cause said primary fluid to flow continuously through said enclosure;   a thermal transfer wall exposed to said primary fluid in said enclosure;   means containing a secondary fluid in flow isolation from said primary fluid and in thermal conduction relationship with said primary fluid through said thermal transfer wall;   rotatable means for mechanically stirring said primary fluid in said enclosure, said rotatable means comprising zone-establishing means for establishing a plurality of thermal zones at successive longitudinal locations in said enclosure, said zone-establishing means comprising:   means in each zone for re-circulating said primary fluid radially from said longitudinal axis, longitudinally along said thermal transfer wall, and radially back to said longitudinal axis, to cause water vapor in said primary fluid to alternately condense on said thermal transfer wall, then be swept away from the wall by the re-circulating primary fluid and then evaporated.   
     
     
       29. Heat exchange apparatus comprising: an enclosure having peripheral walls extending longitudinally between first and second end walls;   inlet means for admitting a primarily gaseous primary fluid into said enclosure proximate said first end;   outlet means for passing said primary fluid out of said enclosure proximate said second end;   fluid flow-inducing means for establishing a relatively low rate of net flow of said primary fluid through said enclosure from said inlet means to said outlet means;   means for containing a secondary fluid isolated from said first fluid;   energy transfer means for providing thermal energy transfer between said primary fluid and said secondary fluid in said enclosure;   a rotatable shaft having a longitudinal axis extending longitudinally through at least a portion of said enclosure;   blade means responsive to rotation of said shaft for swirling the primary fluid along a path which is bounded at least in part by said energy transfer means; and   drive means for rotating said shaft about its longitudinal axis to impart a swirl velocity component to said primary fluid which is much larger than said net flow rate.   
     
     
       30. The apparatus according to claim 29 wherein said blade means comprises a plurality of blade assemblies, each fixed to said shaft at mutually spaced longitudinal locations, each blade assembly comprising a plurality of blades extending radially from said shaft. 
     
     
       31. The heat exchanger according to claim 29 wherein said means for containing comprises: a flow duct surrounding said enclosure; and   means for flowing said second fluid through said flow duct in a direction which is generally opposite to the longitudinal net flow direction of said first fluid.   
     
     
       32. The apparatus according to claim 29 wherein said flow-inducing means comprises exhaust pump means disposed in said enclosure for exhausting primary fluid therefrom. 
     
     
       33. The apparatus according to claim 29 wherein said means for containing comprises a flow path adjacent said peripheral walls for said secondary fluid, said apparatus further comprising means for flowing said secondary fluid through said flow path. 
     
     
       34. The method of recovering thermal energy from combustion gases comprising the steps of: flowing said combustion gases through an enclosure at a controllable net flow rate;   establishing by means of rotating blades in an enclosure, a helical flow path for said combustion gases such that the combustion gases are in continuous swirling contact with a thermal transfer wall which isolates said combustion gases from a secondary fluid and such that water vapor present in said gas continuously condenses on said thermal transfer wall and is swept therefrom by the continuous helical flow, thereby transferring latent heat of vaporization to said secondary fluid:   wherein the flow rate of the helical flow component of said combustion gases is very much greater than the net flow rate through said enclosure.   
     
     
       35. A method for increasing convection efficiency in an enclosure having a longitudinal axis, said method comprising the steps of: supplying a substantially gaseous primary fluid at an inlet opening in said enclosure;   establishing a pressure differential between said inlet opening and an outlet opening of said enclosure to establish a continuous flow of primary fluid through said enclosure;   maintaining a secondary fluid in flow isolation from said primary fluid and thermal conduction relationship with said primary fluid through a thermal transfer element;   mechanically stirring said primary fluid in said enclosure, said stirring including the step of imparting a rotative flow component to said primary fluid about said longitudinal axis and along said thermal transfer element, the rate of said rotative flow component being at least very much greater than the primary fluid net flow rate through said enclosure; and   flowing said secondary fluid through a confined flow path bounded at least in part by said thermal transfer element;   wherein the mechanical stirring of said primary fluid is accomplished by the steps of:   rotating a rotatable shaft about said longitudinal axis; and   rotating plural blade members together with said shaft about said longitudinal axis to provide a net helical flow for said primary fluid through said enclosure, said helical flow representing the vectorial sum of said longitudinal flow and said rotatable shaft.   
     
     
       36. The method according to claim 35 wherein said step of establishing a pressure differential comprises rotating exhauster blades secured to said rotatable shaft in said enclosure to force fluid flow from said inlet opening to said outlet opening. 
     
     
       37. The method according to claim 35 wherein said step of establishing a pressure differential is performed externally of said enclosure. 
     
     
       38. A method of heat exchange comprising the steps of: establishing flow of a first gaseous fluid containing water vapor through an enclosure in contact with a thermal transfer wall;   flowing a second fluid in contact with said thermal transfer wall to permit thermal transfer between said first and second fluids;   establishing a plurality of thermal zones at successive longitudinal locations in said enclosure;   graduating the temperatures in successive zones along the length of said enclosure;   in each zone, swirling said first fluid therein along a path which in part includes said thermal transfer wall;   in each zone, condensing said water vapor on said thermal transfer wall;   sweeping condensed water back into the swirling flow;   vaporizing the water swept back into the swirling flow; and   repeating the above three steps to establish a cycle of condensation and vaporization in each of said zones;   wherein said step of swirling comprises the steps of: rotating a first plurality of blades at a first location about an axis extending along the nominal flow direction of said first fluid through said enclosure; and   in response to rotation of said plurality of blades, establishing a pair of said zones, one upstream and the other downstream of said first plurality of blades, each zone being defined by plural flow components having a net flow pattern which extends radially from said axis then along said thermal transfer wall and then back toward said axis.     
     
     
       39. A method of heat exchange comprising the steps of: establishing flow of a first fluid through a enclosure in contact with a thermal transfer wall;   flowing a second fluid in contact with said thermal transfer wall to permit thermal transfer between said first and second fluids;   establishing a plurality of thermal zones at successive longitudinal locations in said enclosure;   graduating the temperatures in successive zones along the length of said enclosure; and   in each zone, swirling said first fluid therein along a path which in part includes said thermal transfer wall;   wherein said step of swirling comprises the steps of: rotating a first plurality of blades at a first location about an axis extending along the nominal flow direction of said first fluid through said enclosure; and   in response to rotation of said plurality of blades, establishing a pair of said zones, one upstream and the other downstream of said first plurality of blades, each zone being defined by plural flow components having a net flow pattern which extends radially from said axis then along said thermal transfer wall and then back toward said axis.     
     
     
       40. The method according to claim 39 wherein the flow along said thermal transfer wall is oppositely directed in said two zones. 
     
     
       41. In a process of efficiently utilizing accessory power to maximize the convective heat exchange between a flowing gaseous stream and a heat exchanger housing, the steps comprising: maintaining a static pressure differential between a first end and a second end of the heat exchanger housing which provides negligible internal flow resistance to said gaseous stream to flow the gaseous stream from the first end to the second end of the heat exchanger housing at an average axial velocity;   driving a mechanical stirring element located within the gaseous stream from a location outside the stream; and   mechanically stirring the gaseous stream with said stirring element along the inner surface of the heat exchanger housing at an angular velocity which is large relative to said axial velocity of the gaseous stream;   wherein accessory power required to maintain the static pressure differential across the heat exchanger is low and the power required to drive the stirring element is fully utilized to augment the convective heat exchange process.   
     
     
       42. The apparatus according to claim 7 wherein said exhauster blade means is disposed proximate said outlet opening. 
     
     
       43. The apparatus according to claim 29 wherein said fluid flow-inducing means is an exhauster means disposed proximate said outlet means. 
     
     
       44. The apparatus according to claim 43 wherein said exhauster means is a plurality of exhauster fan blades secured to and extending radially from said rotatable shaft. 
     
     
       45. The apparatus according to claim 1 wherein said enclosure is cylindrical and disposed concentrically about said longitudinal axis. 
     
     
       46. The apparatus according to claim 29 wherein said enclosure is cylindrical and disposed concentrically about said longitudinal axis.